From Watford Junction train to London Euston, walk to St Pancras International, then train to Stratford International. 48 min £13. From Watford, Beechen Grove line 142 bus to Stanmore Underground Station then Tube to Stratford Underground Station. 1 h 32 min £7. From Watford taxi to Queen Elizabeth Olympic Park. 39 min £118. From Watford drive to Queen Elizabeth Olympic Park. 39 min £5.